Access to natural and artificial passages in the body for treatment or investigation for possible treatment traditionally make use of elongated instruments that are inserted into the body. These instruments can be inserted into the body alone (e.g., as in a biopsy needle) or may make use of other implements such as an endoscope (e.g., a bronchoscope or colonoscope) through which the elongated instruments are inserted. Typical devices for access to natural or artificial passages in the body may include, for example, spring loaded biopsy “guns,” endoscopic biopsy forceps, biopsy needles, polypectomy snares, cytology brushes, biliary guidewires, sphincterotomes, endoscopic retrograde cholangiography (ERCP) catheters, stone retrieval balloons, stents, lithotripsy baskets, graspers, baskets, rat-tooth and alligator forceps, sclerotherapy/injection needles, bipolar coagulation probes, dilation balloons, radiofrequency ablation devices, microwave ablation devices, cryotherapy probes, or other devices.
Many of these devices have a mechanical or electrical component located near the tip to perform some actuation of a treatment apparatus such as, for example, movement of a set of biopsy jaws or grasper, delivery of energy, actuation of a biopsy mechanism, or other actuation. Directing the tip of these devices into locations of interest, such as those identified preoperatively or intraoperatively through medical scans of the patient (such as CT, MR, PET, SPECT, x-ray etc.) can be difficult. This is especially true if, among other things, the location of the instrument relative to a lesion or other area of interest cannot be visualized directly. If the tip of an instrument is not properly positioned, multiple problems can arise such as, for example, iatrogenic damage to tissue can be imparted, samples of tissue can be obtained that are not the intended target of the procedure, or other problems.
Sometimes, the location of a target lesion or other area of interest is known on a preoperative scan but insufficient landmarks are identifiable during the actual surgical intervention to easily locate the lesion or area of interest. This is especially true if the lesion or area of interest does not appear distinctly different from surrounding tissues under readily available intraoperative imaging modalities. These intraoperative imaging modalities may include x-rays, optical examination or ultrasound. When used, the lesion, area of interest, and/or instrument may be invisible or inaccessible to the “live” (i.e., intraoperative) imaging modality, may appear in insufficient resolution, or the image of the lesion might be degraded through the presence of intervening anatomy. This may render it difficult or impossible to determine the location of the instrument relative to the lesion or area of interest using traditional intraoperative imaging. Furthermore, some imaging modalities, such as those that are based on x-rays, may impart ionizing radiation or be otherwise harmful to patient and surgeon. Even when the intraoperative imaging modalities are able to render a lesion or area of interest and instrument, the images produced can sometimes be difficult to interpret or can take excessive time to obtain. Furthermore, the imaging modalities used for the initial preoperative scans may be inappropriate or otherwise unavailable for use intraoperatively (i.e., during the actual interventional procedure).
For these and other reasons, it is desirable to construct systems, devices and methods for performing interventions where an instrument's tip location can be tracked while inside the patient and a representation of the instrument can be displayed on preoperative or intra-operative scans in which the salient anatomy is visible. It is further desirable that such systems, devices, and methods are usable with flexible instruments to perform the intervention, and that these instruments perform and function similarly to conventional instruments. It is further desirable to use such methods to track instruments that contain a therapy or tissue sampling component at the tip. It is further desirable that these operate in both soft and hard tissue.